Generally, a fluorescent light is the most commonly used lighting equipment in a home or an office because it has low power consumption and very high brightness, compared to a general incandescent lamp. A fluorescent light is a type of discharge lamp. When electric discharges are generated by applying high voltage to the electrodes (filaments) of the fluorescent tube of a fluorescent light, a large number of electrons are emitted and absorbed by fluorescent material applied to the inner surface of the fluorescent tube, so that the fluorescent material emits light, thereby exhibiting the inherent brightness of the fluorescent light.
A general preheating type fluorescent light, as illustrated in FIG. 1, includes a choke transformer 10, a glow start lamp (hereinafter starter lamp) 20, and a fluorescent tube 30. Filaments 32, that is, the electrodes of the fluorescent tube 30, are coated with electron emission material, and must be heated until the electron emission material is activated. When a power switch is turned on, the starter lamp 20 preheats the filaments until the tube emits light due to electric discharges, so that the fluorescent light is turned on. The choke transformer 10 is a device for generating high voltage required for electric discharges.
In a general method of turning on a fluorescent light, when a user turns on a light switch, one of the power supply lines is connected to the starter lamp 20 through the choke transformer 10, and the other of the power supply lines is connected to the starter lamp 20 through the filaments 32 formed in both sides of the fluorescent tube 30, so that voltage is applied to both sides of the starter lamp 20 at the time of applying the voltage. When the voltage is applied to the starter lamp 20, the starter lamp 20 is turned on. At this time, a bimetal lead 22, which is formed inside the starter lamp 20, is physically deformed due to heat generated by the turning on of the starter lamp 20, so that both sides of the starter lamp 20 are short-circuited. When both sides of the starter lamp 20 are short-circuited, voltage is applied to the filaments of both sides of the fluorescent tube 30 via the chock transformer 10. When the voltage is applied to both sides of the fluorescent tube 30, the filaments formed in both sides of the fluorescent tube 30 are heated. Therefore, as the power supplied to the starter lamp 20 decreases, the starter lamp 20 ceases to generate discharges and is turned off. Due to the turning off of the starter lamp 20, the heating of filaments is stopped and, therefore, the bimetal lead 22 formed inside the starter lamp 20 is deformed, so that both sides of the starter lamp 20 are disconnected from each other from a circuit viewpoint. When both sides of the starter lamp 20 are disconnected from each other from a circuit viewpoint, the supply of current to the starter lamp 20 through the filaments 32 is stopped, so that high voltage is induced between the two filaments 32. The fluorescent tube 30 starts to generate discharges due to the voltage induced between two filaments 32 of the fluorescent tube 30, and a large number of electrons are then emitted. When the electrons are absorbed by fluorescent material applied to the inner surface of the fluorescent tube, the fluorescent tube 30 emits light.
When the fluorescent tube 30 emits light, the power that is supplied to the starter lamp 20 decreases and then the starter lamp 20 does not generate discharges, thereby maintaining its initial state.
The method of turning on a fluorescent light using the discharge-type starter lamp 20 has disadvantages in that the operation of the starter lamp varies depending on temperature variation and input voltage, the lifetime of the fluorescent tube 30 is shortened due to the unstable supply of power that is caused by unstable operation attributable to the difference between the product qualities of a starter lamp and the period of use of the starter lamp, and the efficiency of power use decreases due to the use of the method of converting voltage using the choke transformer 10.
In order to resolve the above-described problems, an electronic ballast stabilizer composed of an electric circuit was invented. As illustrated in FIG. 2, the electronic ballast stabilizer converts AC power received from a rectification unit 50 into DC power, oscillates the converted DC power at 30 KHz˜100 KHz through an oscillation unit 60, and switches the oscillated DC power to the primary coil of a transformer 80 for transforming voltage using a switching unit 70. The secondary coil of the transformer 80 generates discharges by applying current-limited high voltage to both sides of a fluorescent tube 90, while heating the filaments of the fluorescent tube 90 using the voltage induced from the primary coil, thereby turning on the fluorescent tube 90.
The above-described electronic ballast stabilizer uses power transformation and switching. The electronic ballast stabilizer has superior power efficiency compared to the method using a discharge type starter lamp. However, there are disadvantages in that power efficiency still decreases due to the power transformation, the components of a switching unit are expensive, the components emit a large amount of heat, and the miniaturization of the components is difficult, so that the miniaturization of a ballast stabilizer circuit is not easy, thereby increasing manufacturing cost and therefore causing low economic efficiency.